bash：如何打印和运行其中包含管道运算符|的cmd数组 [英] Bash: how to print and run a cmd array which has the pipe operator, |, in it

问题描述

这是我这里问题的后续问题：How to write bash function to print and run command when the command has arguments with spaces or things to be expanded

假设我有以下函数来打印并运行存储在数组中的命令：

# Print and run the cmd stored in the passed-in array
print_and_run() {
    echo "Running cmd:  $*"
    # run the command by calling all elements of the command array at once
    "$@"
}

此操作正常：

cmd_array=(ls -a /)
print_and_run "${cmd_array[@]}"

但这不起作用：

cmd_array=(ls -a / | grep "home")
print_and_run "${cmd_array[@]}"

错误：syntax error near unexpected token `|'：

eRCaGuy_hello_world/bash$ ./print_and_run.sh 
./print_and_run.sh: line 55: syntax error near unexpected token `|'
./print_and_run.sh: line 55: `cmd_array=(ls -a / | grep "home")'

如何使此概念与命令中的管道运算符(|)一起使用？

推荐答案

如果要将仅包含|的数组元素视为生成管道的指令，则可以这样做。我不建议使用--这意味着如果您不验证字符串中的变量不能只由单个管道字符组成，就会有安全风险--但这是可能的。

下面，我们创建了一个随机单次使用信号，以使攻击更加困难。如果您不愿意这样做，请将[[ $arg = "$pipe" ]]更改为[[ $arg = "|" ]]。

# generate something random to make an attacker's job harder
pipe=$(uuidgen)

# use that randomly-generated sigil in place of | in our array
cmd_array=(
  ls -a /
  "$pipe" grep "home"
)

exec_array_pipe() {
  local arg cmd_q
  local -a cmd=( )
  while (( $# )); do
    arg=$1; shift
    if [[ $arg = "$pipe" ]]; then
      # log an eval-safe copy of what we're about to run
      printf -v cmd_q '%q ' "${cmd[@]}"
      echo "Starting pipeline component: $cmd_q" >&2
      # Recurse into a new copy of ourselves as a child process
      "${cmd[@]}" | exec_array_pipe "$@"
      return
    fi
    cmd+=( "$arg" )
  done
  printf -v cmd_q '%q ' "${cmd[@]}"
  echo "Starting pipeline component: $cmd_q" >&2
  "${cmd[@]}"
}

exec_array_pipe "${cmd_array[@]}"

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